Semiconductor device structure

ABSTRACT

A semiconductor device structure includes a first chip including a plurality of dielectric layers and a multi-layered metal structure embedded in the plurality of dielectric layer, a second chip bonded to the first chip to generate a bonding interface and including a metal structure, a first via structure extending through the first chip and crossing the bonding interface into the metal structure in the second chip, and a second via structure extending in the first chip and electrically connected to the multi-layered metal structure in the first chip. The first via structure further includes a first via metal and a first via dielectric layer, the first via dielectric layer interposes between the first via metal and the plurality of dielectric layers of the first chip and extends from the first chip to the metal structure in the second chip.

PRIORITY CLAIM AND CROSS-REFERENCE

This application is a continuation of U.S. patent application Ser. No. 14/832,321, entitled “METHOD OF MANUFACTURING A SEMICONDUCTOR DEVICE” filed on Aug. 21, 2015, which is a divisional of U.S. patent application Ser. No. 14/244,719, filed on Apr. 3, 2014, entitled “SEMICONDUCTOR DEVICE AND MANUFACTURING METHOD THEREOF,” which is a non-provisional application of U.S. Provisional Application No. 61/921,753 filed on Dec. 30, 2013, which is incorporated herein by reference.

BACKGROUND

Electronic equipment using semiconductor devices are essential for many modern applications. With the advancement of electronic technology, electronic equipment is becoming increasingly smaller in size while having greater functionality and greater amounts of integrated circuitry. Thus, semiconductor devices inside the electronic equipment are also becoming denser, smaller and more compact. The continuous demands for a size reduction of semiconductor devices has made it necessary to develop more integrated circuits that can be accommodated within the semiconductor devices.

The major trend in the electronic industry is to make the semiconductor devices smaller and more multifunctional. Thus, a semiconductor device comprises an electrical interconnection structure for electrically connecting a number of metallic structures between adjacent layers of the semiconductor device so as to minimize the final size of the semiconductor device as well as the electronic equipment. The electrical interconnection structure includes a number of trenches or vias which are filled with a conductive material, such as copper or aluminum, and are pierced through several adjacent layers in the semiconductor device in order to connect circuits between adjacent layers.

However, manufacturing of the electrical interconnection structure is complicated because it involves numerous manufacturing operations and those operations are applied on the semiconductor device, which includes many different kinds of materials with different properties. The differences between the materials would increase the complexity of manufacturing the semiconductor devices and may cause deficiencies. Such deficiencies may include poor bondability between layers, poor reliability of the trenches, and cracking or delamination of the electrical interconnection structure. As such, there is a continuous need to improve the method for manufacturing the electrical interconnection structure so as to solve the above deficiencies.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 is a schematic view of a semiconductor device including a first semiconductor chip and a second semiconductor chip in accordance with some embodiments of the present disclosure.

FIG. 1A is a schematic view of a first insulating layer inside a first semiconductor chip in accordance with some embodiments of the present disclosure.

FIG. 2 is a schematic view of a semiconductor device including a first recessed portion and a second recessed portion in a stepped configuration in accordance with some embodiments of the present disclosure.

FIG. 2A is a schematic view a semiconductor device including a first semiconductor chip, a second semiconductor chip and a metal plug in accordance with some embodiments of the present disclosure.

FIG. 3 is a flow diagram of a method of manufacturing a semiconductor device in accordance with some embodiments of the present disclosure.

FIG. 3A is a schematic view of provision of a first semiconductor chip in accordance with some embodiments of the present disclosure.

FIG. 3B is a schematic view of provision of a second semiconductor chip in accordance with some embodiments of the present disclosure.

FIG. 3C is a schematic view of bonding a first semiconductor chip with a second semiconductor chip in accordance with some embodiments of the present disclosure.

FIG. 3D is a schematic view of forming a first recessed portion in accordance with some embodiments of the present disclosure.

FIG. 3E is a schematic view of forming a second recessed portion in accordance with some embodiments of the present disclosure.

FIG. 3F is a schematic view of forming a dielectric layer in accordance with some embodiments of the present disclosure.

FIG. 3G is a schematic view of removing a portion of a dielectric layer in accordance with some embodiments of the present disclosure.

FIG. 3H is a schematic view of forming a conductive material in accordance with some embodiments of the present disclosure.

FIG. 4 is a flow diagram of a method of manufacturing a semiconductor device in accordance with some embodiments of the present disclosure.

FIG. 4A is a schematic view of provision of a first semiconductor chip in accordance with some embodiments of the present disclosure.

FIG. 4B is a schematic view of provision of a second semiconductor chip in accordance with some embodiments of the present disclosure.

FIG. 4C is a schematic view of bonding a first semiconductor chip with a second semiconductor chip in accordance with some embodiments of the present disclosure.

FIG. 4D is a schematic view of forming a first recessed portion in accordance with some embodiments of the present disclosure.

FIG. 4E is a schematic view of forming a second recessed portion in accordance with some embodiments of the present disclosure.

FIG. 4F is a schematic view of forming a dielectric layer in accordance with some embodiments of the present disclosure.

FIG. 4G is a schematic view of removing a portion of a dielectric layer in accordance with some embodiments of the present disclosure.

FIG. 4H is a schematic view of forming a conductive material in accordance with some embodiments of the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

A semiconductor device is manufactured by a number of operations. During the manufacturing, an electrical interconnection structure is formed between a number of conductive metallic structures across a number of insulating layers of at least two semiconductor chips in the semiconductor device. The conductive metallic structures are connected with each other by piercing a number of trenches or vias from a semiconductor chip to another semiconductor chip. The trench is formed by etching through the semiconductor chips. The trench is then coated or filled with a conductive material, so that the conductive metallic structures are electrically connected across the semiconductor chips through the trench coated or filled with the conductive material.

However, the insulating layers of a semiconductor chip include various kinds of materials such as silicon oxide, black diamond (Black Diamond® (Applied Materials of Santa Clara. Calif.)) and silicon carbide etc. which have different etch rates to a predetermined etchant. As such, a lateral etching of sidewall of the trench is suffered. The lateral etching leads to an uneven and rough sidewall surface and thus induces a poor reliability upon disposition of the conductive material on the sidewall of the trench.

The manufacturing and use of the embodiments of the present disclosure are discussed in details below. It should be appreciated, however, that the embodiments provide many applicable inventive concepts that can be embodied in a wide variety of specific contexts. It is to be understood that the following disclosure provides many different embodiments or examples for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting.

Embodiments, or examples, illustrated in the drawings are disclosed below using specific language. It will nevertheless be understood that the embodiments and examples are not intended to be limiting. Any alterations and modifications in the disclosed embodiments, and any further applications of the principles disclosed in this document are contemplated as would normally occur to one of ordinary skill in the pertinent art.

Further, it is understood that several processing steps and/or features of a device may be only briefly described. Also, additional processing steps and/or features can be added, and certain of the following processing steps and/or features can be removed or changed while still implementing the claims. Thus, the following description should be understood to represent examples only, and are not intended to suggest that one or more steps or features is required.

In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

In the present disclosure, a semiconductor device with an improved electrical interconnection structure is disclosed. The electrical interconnection structure includes a recessed portion which is coated with an oxide layer in order to improve a smoothness of a sidewall surface of the recessed portion and thus prevent the poor reliability of the electrical interconnection structure and yield loss of the semiconductor device.

FIG. 1 is a diagram of a semiconductor device 100 in accordance with various embodiments of the present disclosure. The semiconductor device 100 includes a first semiconductor chip 101-1. The first semiconductor chip 101-1 includes a first substrate 101 g, a first insulating layer 103-1 and a first metallic structure 102 a-1 disposed within the first insulating layer 103-1.

In some embodiments, the first semiconductor chip 101-1 is a semiconductor sensor chip. In some embodiments, the first semiconductor chip 101-1 is fabricated by a complementary metal-oxide-semiconductor (CMOS) process techniques known in the art to become a CMOS image sensor (CIS) chip. The CIS chip is widely used in a digital camera application. The CIS chip is configured for capturing a light and converting the light into an electrical signal.

In some embodiments, the first semiconductor chip 101-1 comprises an epitaxial (EPI) layer (not shown) over a silicon substrate, and the silicon substrate is removed during a backside thinning operation until the EPI layer is exposed. In some embodiments, a portion of the EPI is remained. In some embodiments, a p-type photo active region and an n-type photo active region (not shown respectively) are formed in the remaining epitaxial layer.

In some embodiments, the first semiconductor chip 101-1 includes a transistor (not shown) which generates a signal related to an intensity or a brightness of a light projected on the photo active regions. In some embodiments, the transistor may be a transfer transistor. However, the transistor may be an example of the many types of functional transistors utilized within the first semiconductor chip 101-1. In some embodiments, the transistor may include other transistors such as a reset transistor, a source follower transistor or a select transistor. All suitable transistors and configurations utilized in the first semiconductor chip 101-1 are fully intended to be included within the scope of the embodiments.

In some embodiments, the first substrate 101 g of the first semiconductor chip 101-1 includes silicon, germanium, gallium, arsenic, and combinations thereof. In some embodiments, the first substrate 101 g is in a form of silicon-on-insulator (SOI) including a layer of a semiconductor material (e.g., silicon, germanium and/or the like) formed over an insulator layer (e.g., buried oxide and/or the like). In some embodiments, the first substrate 101 g includes multi-layered substrates, gradient substrates, hybrid orientation substrates, any combinations thereof and/or the like.

In some embodiments, the first substrate 101 g comprises a variety of electrical circuits (not shown) formed on the first substrate 102. In some embodiments, the electrical circuits is any one type of circuitries suitable for a particular application. In some embodiments, the electrical circuits includes various n-type metal-oxide semiconductor (NMOS) and/or p-type metal-oxide semiconductor (PMOS) devices such as transistors, capacitors, resistors, diodes, photo-diodes, fuses and/or the like. In some embodiments, the electrical circuits may be interconnected to perform one or more functions including memory structures, processing structures, sensors, amplifiers, power distribution, input/output circuitry and/or the like. One of ordinary skill in the art will appreciate that the above examples are provided for illustrative purposes only and are not intended to limit the various embodiments to any particular applications.

In some embodiments, the first insulating layer 103-1 is an inter-metal dielectric (IMD) layer including a dielectric material for isolating a number of conductive metallic structures from each other inside the first insulating layer 103-1. In some embodiments, the first insulating layer 103-1 includes at least two adjacent layers differing in etch rates to a predetermined etchant. In some embodiments, the at least two adjacent layers have difference in materials with different etch rates around 700 nm/min to a predetermined etchant CF4 gas. The layers are removed in different rates under the predetermined etchant upon the etching operation. In some embodiments, the at least two adjacent layers include a silicon oxide layer, silicon carbide layer and a black diamond (Black Diamond® (Applied Materials of Santa Clara, Calif.) layer, which have different etch rates from each other.

In some embodiments, the first metallic structure 102 a-1 of the first semiconductor chip 101-1 is disposed within the first insulating layer 103-1. The first insulating layer 103-1 encapsulates the first metallic structure 102 a-1. In some embodiments, the first metallic structure 102 a-1 includes gold, silver, copper, nickel, tungsten, aluminum, palladium and/or alloys thereof. In some embodiments, the first metallic structure 102 a-1 is a portion of a first metal interconnection of the first semiconductor chip 101-1.

In some embodiments, the semiconductor device 100 includes a second semiconductor chip 101-2. In some embodiments, the first semiconductor chip 101-1 is bonded with the second semiconductor chip 101-2. In some embodiments, the first semiconductor chip 101-1 and the second semiconductor chip 101-2 are bonded together through any suitable bonding techniques such as direct bonding. In some embodiments, the first semiconductor chip 101-1 is bonded by an interface 101 f between the first semiconductor chip 101-1 and the second semiconductor chip 101-2. In some embodiments, the first semiconductor chip 101-1 and the second semiconductor chip 101-2 are bonded together by a metal-to-metal bonding (e.g., copper-to-copper bonding), dielectric-to-dielectric bonding (e.g., oxide-to-oxide bonding), metal-to-dielectric bonding (e.g., oxide-to-copper bonding), any combinations thereof and/or the like.

In some embodiments, the interface 101 f is between a passivation layer 101 d of the first semiconductor chip 101-1 and a passivation layer 101 e of the second semiconductor chip 101-2. In some embodiments, the passivation layer 101 d and the passivation layer 101 e are respectively an oxide layer including silicon oxide. In some embodiments, the passivation layer 101 d and the passivation layer 101 e respectively includes silicon nitride. In some embodiments, the passivation layer 101 d and the passivation layer 101 e respectively includes a composite structure, hybrid bond, bonding interface including metal such as copper, and dielectric such as silicon oxide or silicon nitride.

In some embodiments, the second semiconductor chip 101-2 is a semiconductor application specific integrated circuit (ASIC) chip which is configured for a particular application. In some embodiments, the second semiconductor chip 101-2 includes several logic circuits such as an analog-to-digital converter, a data processing circuit, a memory circuit, a bias circuit, a reference circuit, any combinations thereof and/or the like.

In some embodiments, the second semiconductor chip 101-2 includes a second substrate 101 h, a second insulating layer 103-2 and a second metallic structure 102 a-2. In some embodiments, the second substrate 101 h includes silicon, germanium, gallium, arsenic, and combinations thereof. In some embodiments, the second substrate 101 h is in a form of silicon-on-insulator (SOI). In some embodiments, the second substrate 101 h is multi-layered substrates, gradient substrates, hybrid orientation substrates, any combinations thereof and/or the like.

In some embodiments, the second substrate 101 h includes a variety of electrical circuits (not shown). The electrical circuits formed on the second substrate 101 h are configured for a particular application. In some embodiments, the electrical circuits may be interconnected to perform one or more functions such as memory structures, processing structures, sensors, amplifiers, power distribution, input/output circuitry and/or the like. One of ordinary skill in the art will appreciate that the above examples are provided for illustrative purposes only and are not intended to limit the various embodiments to any particular applications.

In some embodiments, the second insulating layer 103-2 is an inter-metal dielectric (IMD) layer including a dielectric material for isolating a number of conductive metallic structures from each other inside the second insulating layer 103-2. In some embodiments, the second insulating layer 103-2 includes various dielectric materials commonly used in integrated circuit fabrication. In some embodiments, the second insulating layer 103-2 includes silicon dioxide, silicon nitride or a doped glass layer such as boron silicate glass and the like. In some embodiments, the second insulating layer 103-2 is formed using suitable techniques such as sputtering, oxidation, CVD and/or the like.

In some embodiments, the second metallic structure 102 a-2 of the second semiconductor chip 101-2 is disposed within the second insulating layer 103-2. The second insulating layer 103-2 encapsulates the second metallic structure 102 a-2. In some embodiments, the second metallic structure 102 a-2 includes gold, silver, copper, nickel, tungsten, aluminum, palladium and/or alloys thereof. In some embodiments, the second metallic structure 102 a-2 is a portion of a first metal interconnection of the second semiconductor chip 101-2.

In some embodiments, the first semiconductor chip 101-1 includes a top surface 101 a. The top surface 101 a includes a first recessed portion 106-1 and a second recessed portion 106-2. In some embodiments, the first recessed portion 106-1 includes a first sidewall 103 d-1 along the first recessed portion 106-1. In some embodiments, the top surface 101 a includes a first recessed portion 106-1 extended from the top surface 101 a to the first metallic structure 102 a-1. In some embodiments, the first recessed portion 106-1 is extended from the top surface 101 a to a portion 102 b-1 of the first metallic structure 102 a-1 disposed on or within the first metallic structure 102 a-1. In some embodiments, the portion 102 b-l of the first metallic structure 102 a-1 is coplanar with a bottom surface of the first recessed portion 106-1. In some embodiments, the first recessed portion 106-1 is configured in a cylindrical shape with a circular cross-section.

In some embodiments, the first metallic structure 102 a-1 includes suitable metallic materials such as copper, which is of a different etching rate (selectivity) from the first substrate 101 g and the first insulating layer 103-1. As such, the first metallic structure 102 a-1 is functioned as a hard mask layer for an etching operation of the first insulating layer 103-1. In some embodiments, a selective etching operation is employed to etch the first insulating layer 103-1 rapidly, while a portion 102 b-1 of the first metallic structure 102 a-1 is partially etched away, thereby forming the first recessed portion 106-1 and forming the bottom surface of the first recessed portion 106-1 on or within the first metallic structure 102 a-1. The depth of the first recessed portion 106-1 varies depending on different applications and design needs.

In some embodiments, the first recessed portion 106-1 includes a depth D_(first recess) from the top surface 101 a of the first semiconductor chip 101 to the portion 102 b-1 of the first metallic structure 102 a-1. In some embodiments, the depth D_(first recess) of the first recessed portion 106-1 is about 1 um to about 5 um.

In some embodiments, the first recessed portion 106-1 includes a width W_(first recess) between the first sidewall 103 d-1. In some embodiments, the width W_(first recess) of the first recessed portion 106-1 is about 5 um to about 12 um.

In some embodiments, the second recessed portion 106-2 is extended from the top surface 101 a towards the second metallic structure 102 a-2. In some embodiments, the second recessed portion 106-2 passes through the first semiconductor chip 101-1 and the second semiconductor chip 101-2. In some embodiments, the second recessed portion 106-2 includes a second sidewall 103 d-2 surrounded by the at least two adjacent layers of the first insulting layer 103-1 with different materials. In some embodiments, the portion 102 b-2 of the second metallic structure 102 a-2 is coplanar with a bottom surface of the second recessed portion 106-2. In some embodiments, the second recessed portion 106-2 is configured in a cylindrical shape with a circular cross-section.

In some embodiments, the second metallic structure 102 a-2 includes suitable metallic materials such as copper, which is of a different etching rate (selectivity) from the second substrate 101 h and the second insulating layer 103-2. As such, the second metallic structure 102 a-2 is functioned as a hard mask layer for an etching operation of the second insulating layer 103-2. In some embodiments, a selective etching operation is employed to etch the second insulating layer 103-2 rapidly, while a portion 102 b-2 of the second metallic structure 102 a-2 is partially etched away, thereby forming the second recessed portion 106-2 and forming the bottom surface of the second recessed portion 106-2 on or within the second metallic structure 102 a-2. The depth of the second recessed portion 106-2 varies depending on different applications and design needs.

In some embodiments, the second recessed portion 106-2 includes a depth D_(second recess) from the top surface 101 a of the first semiconductor chip 101 to the portion 102 b-2 of the second metallic structure 102 a-2. In some embodiments, the depth D_(second recess) of the second recessed portion 106-2 is about 6 um to about 12 um.

In some embodiments, the second recessed portion 106-2 includes a width W_(second recess) between the second sidewall 103 d-2. In some embodiments, the width W_(second recess) of the second recessed portion 106-2 is about 5 um to about 12 um.

In some embodiments, the second recessed portion 106-2 includes a number of staggered portions 103 e on a second sidewall 103 d-2 of the second recessed portion 106-2 surrounded by the first insulating layer 103-1. As the first insulating layer 103-1 includes various kinds of materials with different etch rates, the number of staggered portions 103 e are disposed on the second sidewall 103 d-2 along the second recessed portion 106-2.

FIG. 1A is an enlarged view of an embodiment of the staggered portions 103 e of the second recessed portion 106-2 in accordance with various embodiments of the present disclosure. In some embodiments, the staggered portions 103 e are surrounded by the first insulating layer 103-1 of the first semiconductor chip 101-1. In some embodiments, the first insulating layer 103-1 includes a silicon carbide layer 103 a and a black diamond layer 103 b which are spaced in an interval. In some embodiments, the second recessed portion 106-2 is formed by etching some of the silicon carbide layer 103 a and some of the black diamond layer 103 b. The etch rate of the black diamond layer 103 b is faster than the etch rate of the silicon carbide layer 103 a 700 nm/min to a predetermined etchant CF4.

As the difference in the etch rates of the silicon carbide layer 103 a and the black diamond layer 103 b, the second sidewall 103 d-2 of the first insulating layer 103-1 includes the number of staggered portions 103 e along the second sidewall 103 d-2 of the second recessed portion 106-2. In some embodiments, the black diamond layer 103 b is recessed laterally relative to the silicon carbide layer 103 a with a depth which is a length l_(staggered) as shown in FIG. 1A. In some embodiments, the staggered portions 103 e surrounded by the black diamond layer 103 b is laterally indented towards an exterior 103 f of the first insulating layer 103-1. The staggered portion 103 e surrounded by the silicon carbide layer 103 a is laterally protruded towards the second recessed portion 106-2. In some embodiments, the silicon carbide layer 103 a protruded from the black diamond layer 103 b is in the length l_(staggered) about 46 nm to about 76 nm. In some embodiments, the length l_(staggered) is about 40 nm to about 80 nm.

Referring back to FIG. 1, in some embodiments, a dielectric layer 104 is disposed on the top surface 101 a of the first semiconductor chip 101-1, the first sidewall 103 d-1 of the first recessed portion 106-1 and the second sidewall 103 d-2 of the second recessed portion 106-2. In some embodiments, some portions of the dielectric layer 104 are disposed within the staggered portions 103 e. In some embodiments, the portion 102 b-1 of the first metallic structure 102 a-1 and the portion 102 b-2 of the second metallic structure 102 a-2 are not covered by the dielectric layer 104. In some embodiments, the dielectric layer 104 is an oxide layer which includes a plasma enhanced oxide (PEOX). In some embodiments, the dielectric layer 104 includes a non-conductive material such as silicon dioxide. In some embodiments, the dielectric layer 104 is formed using suitable techniques such as sputtering, oxidation or etc.

In some embodiments, a conductive material 105 covers the dielectric layer 104, the portion 102 b-1 of the first metallic structure 102 a-1 in the first semiconductor chip 101-1 and the portion 102 b-2 of the second metallic structure 102 a-2 in the second semiconductor chip 101-2. In some embodiments, the first metallic structure 102 a-1 of the first semiconductor chip 101-1 is configured for electrically connecting with the second metallic structure 102 a-2 in the second semiconductor chip 101-2. As such, the first metallic structure 102 a-1 is electrically connected with the second metallic structure 102 a-2 along the conductive material 105. In some embodiments, the conductive material 105 is coated on the dielectric layer 104, the portion 102 b-1 of the first metallic structure 102 a-1 and the portion 102 b-2 of the second metallic structure 102 a-2 by electroplating or sputtering or etc. The conductive material 105 is a metallic coating including gold, silver, copper, nickel, tungsten, aluminum, palladium and/or alloys thereof. In some embodiments, a thickness T_(conductive) of the conductive material 105 is about 4 kA to 12 kA.

FIG. 2 is a diagram of a semiconductor device 100 in accordance with various embodiments of the present disclosure. In some embodiments, the semiconductor device 100 includes a first semiconductor chip 101-1 and a second semiconductor chip 101-2. The first semiconductor chip 101-1 includes a top surface 101 a, a first insulating layer 103-1 and a first metallic structure 102 a-1. The second semiconductor chip 101-2 includes a second insulating layer 103-2 and a second metallic structure 102 a-2.

In some embodiments, the first semiconductor chip 101-1 is a CMOS image sensor chip, and the second semiconductor chip 101-2 is an ASIC chip. The first semiconductor chip 101-1 is bonded with the second semiconductor chip 101-2 by the interface 101 f between the first semiconductor chip 101-1 and the second semiconductor chip 101-2. In some embodiments, the first semiconductor chip 101-1 includes the first metallic structure 102 a-1 for electrically connecting with the second metallic structure 102 a-2 in the second semiconductor chip 101-2. The first semiconductor chip 101-1 includes the first insulating layer 103-1 including at least two adjacent layers differing in etch rates to a predetermined etchant.

In some embodiments, the first semiconductor chip 101-1 includes a top surface 101 a. The top surface 101 a includes a first recessed portion 106-1. The first recessed portion 106-1 extends from the top surface 101 a to a portion 102 b-1 of the first metallic structure 102 a-1. In some embodiments, the first recessed portion 106-1 includes a first sidewall 103 d-1 along the first recessed portion 106-1 and a bottom surface disposed on or within the first metallic structure 102 a-1.

In some embodiments, the first metallic structure 102 a-1 includes suitable metallic materials such as copper, which is of a different etching rate (selectivity) from the first substrate 101 g and the first insulating layer 103-1. As such, the first metallic structure 102 a-1 is functioned as a hard mask layer for an etching operation of the first insulating layer 103-1. In some embodiments, a selective etching operation is employed to etch the first insulating layer 103-1 rapidly, while a portion 102 b-1 of the first metallic structure 102 a-1 is partially etched away, thereby forming the first recessed portion 106-1 with a first sidewall 103 d-1. The depth of the first recessed portion 106-1 varies depending on different applications and design needs.

In some embodiments, a second recessed portion 106-2 extends from the portion 102 b-1 of the first metallic structure 102 a-1 to a portion 102 b-2 of the second metallic structure. In some embodiments, the second recessed portion 106-2 includes a second sidewall 103 d-2 along the second recessed portion 106-2 and a bottom surface disposed on or within the second metallic structure 102 a-2. The second recessed portion 106-2 passes through the first semiconductor chip 101-1 and the second semiconductor chip 101-2.

In some embodiments, the second metallic structure 102 a-2 includes suitable metallic materials such as copper, which is of a different etching rate (selectivity) from the second substrate 101 h and the second insulating layer 103-2. As such, the second metallic structure 102 a-2 is functioned as a hard mask layer for an etching operation of the second insulating layer 103-2. In some embodiments, a selective etching operation is employed to etch the second insulating layer 103-2 rapidly, while a portion 102 b-2 of the second metallic structure 102 a-2 is partially etched away, thereby forming the second recessed portion 106-2 with a second sidewall 103 d-2 and forming the bottom surface of the second recessed portion 106-2 on or within the second metallic structure 102 a-2. The depth of the second recessed portion 106-2 varies depending on different applications and design needs.

In some embodiments, the first recessed portion 106-1 and the second recessed portion 106-2 are in a stepped configuration. The first sidewall 103 d-1 and the second sidewall 103 d-2 are in a number of steps from the top surface 101 a of the first semiconductor chip 101-1 towards the second metallic structure 102 a-2. In some embodiments, a first width w_(recess-1) of the first recessed portion 106-1 is larger than a second width w_(recess-2) of the second recessed portion 106-2.

In some embodiments, the first sidewall 103 d-1 surrounded by the first insulating layer 103-1 of the first semiconductor chip 101-1 includes a number of staggered portions 103 e. As the first insulating layer 103-1 includes various kinds of materials with different etch rates, the number of staggered portions 103 e are disposed on the first sidewall 103 d-1 along the first recessed portion 106-1 surrounded by the first insulating layer 103-1.

In some embodiments, the top surface 101 a of the first semiconductor chip 101-1, the first sidewall 103 d-1 of the first recessed portion 106-1 and the second sidewall 103 d-2 of the second recessed portion 106-2 are covered by a dielectric layer 104. In some embodiments, the portion 102 b-1 of the first metallic structure 102 a-1 and the portion 102 b-2 of the second metallic structure 102 a-2 are not covered by the dielectric layer 104. In some embodiments, some portions of the dielectric layer 104 are disposed within the number of staggered portions 103 e. In some embodiments, the dielectric layer 104 is a non-conductive coating which is in a stepped configuration compliance with a profile of the first recessed portion 106-1 and the second recessed portion 106-2.

In some embodiments, the dielectric layer 104, the portion 102 b-1 of the first metallic structure 102 a-1 in the first semiconductor chip 101-1 and the portion 102 b-2 of the second metallic structure 102 a-2 in the second semiconductor chip 101-2 are covered by a conductive material 105, so that the first metallic structure 102 a-1 is electrically connected with the second metallic structure 102 a-2. In some embodiments, the conductive material 105 is a metal coating which is in a stepped configuration conformal over the dielectric layer 104, the portion 102 b-1 and the portion 102 b-2.

In some embodiments, the conductive material 105 is a metal plug disposing and filling the first recessed portion 106-1 and the second recessed portion 106-2 in a stepped configuration as in FIG. 2A. In some embodiments, the metal plug is disposed on the dielectric layer 104, the portion 102 b-1 of the first metallic structure 102 a-1 and the portion 102 b-2 of the second metallic structure 102 a-2 by electroplating. In some embodiments, the metal plug includes gold, silver, copper, nickel, tungsten, aluminum, palladium and/or alloys thereof.

In the present disclosure, a method of manufacturing a semiconductor device is also disclosed. In some embodiments, a semiconductor device is formed by a method 200 or a method 300. The method 200 or the method 300 includes a number of operations and the description and illustration are not deemed as a limitation as the sequence of the operations.

FIG. 3 is a flowchart of a method 200 of manufacturing a semiconductor device. The method 200 includes a number of operations (201, 202, 203, 204, 205, 206, 207 and 208).

In operation 201, a first semiconductor chip 101-1 is provided as in FIG. 3A. The first semiconductor chip 101-1 includes a first metallic structure 102 a-1 inside the first semiconductor chip 101-1 and a top surface 101 a. In some embodiments, the first semiconductor chip 101-1 includes a first insulating layer 103-1 including a various kinds of materials with different etch rates such as silicon carbide, black diamond, etc.

In some embodiments, the first semiconductor chip 101-1 includes a passivation layer 101 d which is disposed opposite to the top surface 101 a of the first semiconductor chip 101-1. In some embodiments, the first semiconductor chip 101-1 is fabricated by a complementary metal-oxide-semiconductor (CMOS) process techniques known in the art to become a CMOS image sensor (CIS) chip.

In operation 202, a second semiconductor chip 101-2 is provided as in FIG. 3B. In some embodiments, the second semiconductor chip 101-2 is an ASIC chip. In some embodiments, the second semiconductor chip 101-2 includes a second metallic structure 102 a-2 inside the second semiconductor chip 101-2. The second semiconductor chip 101-2 includes a second insulating layer 103-2 and a passivation layer 101 e. The passivation layer 101 e is adjacent to an interface 101 f for bonding with the first semiconductor chip 101-1.

In operation 203, the first semiconductor chip 101-1 is bonded with the second semiconductor chip 101-2 as in FIG. 3C. In some embodiments, the first semiconductor chip 101-1 and the second semiconductor chip 101-2 are bonded together through any suitable bonding techniques such as direct bonding. In some embodiments, the first semiconductor chip 101-1 and the second semiconductor chip 101-2 are bonded by the interface 101 f between the passivation layer 101 d of the first semiconductor chip 101-1 and the passivation layer 101 e of the second semiconductor chip 101-2. In some embodiments, the first semiconductor chip 101-1 is bonded with the second semiconductor chip 101-2 through a suitable metal-dielectric bonding technique such as a copper-silicon oxide nitride (Cu—SiON) bonding process.

In operation 204, a first recessed portion 106-1 is formed as in FIG. 3D. The first recessed portion 106-1 is formed from the top surface 101 a of the first semiconductor chip 101-1 towards the first metallic structure 102 a-1, so that a portion 102 b-1 of the first metallic structure 102 a-1 is exposed. The first recessed portion 106-1 includes the first sidewall 103 d-1 and a bottom surface coplanar with the portion 102 b-1 of the first metallic structure 102 a-1. The first recessed portion 106-1 is surrounded by the first insulating layer 103-1. In some embodiments, the bottom surface of the first recessed portion 106-1 is disposed on or within the first metallic structure 102 a-1.

In some embodiments, the first recessed portion 106-1 is formed by etching of the first insulating layer 103-1. The etching is an operation of selectively dissolving and removing one or more kinds of materials by a predetermined etchant such as CF4. Some of the first insulating layer 103-1 are prevented from etching by a masking material such as a photolithography patterned-photoresist to form the first recessed portion 106-1. The first recessed portion 106-1 is formed depending on how long time of the etching operations and which types of etchants are used. In some embodiments, the etch rate of silicon dioxide is 3 um/min, that is a thickness of 3 um of the silicon dioxide is etched away every minute. In some embodiments, the first recessed portion 106-1 is formed by suitable deposition and photolithography techniques such as a reactive ion etch (RIE) or other dry etch, an anisotropic wet etch, any other suitable anisotropic etching or etc.

In operation 205, a second recessed portion 106-2 is formed as in FIG. 3E. In some embodiments, the second recessed portion 106-2 is formed from the top surface 101 a to a portion 102 b-2 of the second metallic structure 102 a-2. The second recessed portion 106-2 passes from the first semiconductor chip 101-1 to the second semiconductor chip 101-2. In some embodiments, the second recessed portion 106-2 includes the second sidewall 103 d-2 and a bottom surface coplanar with the portion 102 b-2 of the second metallic structure 102 a-2. In some embodiments, the bottom surface of the second recessed portion 106-2 is disposed on or within the second metallic structure 102 a-2. In some embodiments, the second recessed portion 106-2 is surrounded by the first insulating layer 103-1. The second recessed portion 106-2 is extended from the top surface 101 a of the first semiconductor chip 101-1 towards the second metallic structure 102 a-2 of the second semiconductor chip 101-2, so that the portion 102 b-2 of the second metallic structure 102 a-2 is exposed.

In some embodiments, the second recessed portion 106-2 is formed by etching of the first insulating layer 103-1. Upon the etching operations, a number of staggered portions 103 e are formed on the second sidewall 103 d-2 of the second recessed portion 106-2 surrounded by the first insulating layer 103-1, because the first insulating layer 103-1 includes various kinds of materials with different etch rates to a predetermined etchant. As such, the sidewall 103 d-1 is in an uneven and rough surface along the second recessed portion 106-2 towards the second metallic structure 102 a-2.

In operation 206, a dielectric layer 104 is formed as in FIG. 3F. In some embodiments, the dielectric layer 104 is coated on the top surface 101 a of the first semiconductor chip 101-1, the first sidewall 103 d-1 of the first recessed portion 106-1, the second sidewall 103 d-2 of the second recessed portion 106-2, the portion 102 b-1 of the first metallic structure 102 a-1 and the portion 102 b-2 of the second metallic structure 102 a-2. In some embodiments, the dielectric layer 104 is a coating including non-conductive material such as silicon dioxide. In some embodiments, the dielectric layer 104 covers and fills the staggered portions 103 e in order to smoothen the rough surface of the second sidewall 103 d-2 of the second recessed portion 106-2.

In operation 207, some portions of the dielectric layer 104 on the portion 102 b-1 of the first metallic structure 101-1 and the portion 102 b-2 of the second metallic structure 101-2 are removed as in FIG. 3G. As some portions of the dielectric layer 104 are not covered by the patterned photoresist, those uncovered portions of the dielectric layer 104 are dissolved and removed by etching by a predetermined etchant, and thus the portion 102 b-1 of the first metallic structure 102 a-1 and the portion 102 b-2 of the second metallic structure 102 a-2 are then exposed.

In operation 208, a conductive material 105 is formed on the dielectric layer 104, the portion 102 b-1 of the first metallic structure 102 a-1 and the portion 102 b-2 of the second metallic structure 102 a-2 as in FIG. 3H. In some embodiments, the conductive material 105 is formed by electroplating or sputtering. The first metallic structure 102 a-1 is then electrically connected with the second metallic structure 102 a-2 via the conductive material 105 passing from the top surface 101 a, the first recessed portion 106-1 to the second recessed portion 106-2. In some embodiments, the conductive material 105 includes gold, silver, copper, nickel, tungsten, aluminum, palladium and/or alloys thereof.

FIG. 4 is an embodiment of a method 300 of manufacturing a semiconductor device. The method 300 includes a number of operations (301, 302, 303, 304, 305, 306, 307 and 308). In some embodiments, operations 201-203 in FIG. 3A-3C are similar to operations 301-303 in FIG. 4A-4C.

In operation 304, a first recessed portion 106-1 is formed as in FIG. 4D. The first recessed portion 106-1 is formed from the top surface 101 a of the first semiconductor chip 101-1 towards the first metallic structure 102 a-1, so that a portion 102 b-1 of the first metallic structure 102 a-1 is exposed. In some embodiments, the first recessed portion 106-1 includes the first sidewall 103 d-1 and a bottom surface coplanar with the portion 102 b-1 of the first metallic structure 102 a-1. In some embodiments, the bottom surface of the first recessed portion 106-1 is disposed on or within the first metallic structure 102 a-1. In some embodiments, the first recessed portion 106-1 is surrounded by the first insulating layer 103-1.

In some embodiments, the first recessed portion 106-1 is formed by etching of the first insulating layer 103-1. The etching is an operation of selectively dissolving and removing one or more kinds of materials by a predetermined etchant. Some of the first insulating layer 103-1 are prevented from etching by a masking material such as a photolithography patterned-photoresist to form the first recessed portion 106-1. The first recessed portion 106-1 is formed depending on how long time of the etching operations and which types of etchants are used. In some embodiments, the first recessed portion 106-1 is formed by suitable deposition and photolithography techniques such as a reactive ion etch (RIE) or other dry etch, an anisotropic wet etch, any other suitable anisotropic etching or etc.

In some embodiments, a number of staggered portions 103 e are formed on the first sidewall 103 d-1 of the first recessed portion 106-1 surrounded by the first insulating layer 103-1 upon the etching operations, because the first insulating layer 103-1 includes various kinds of materials with different etch rates to a predetermined etchant. As such, the first sidewall 103 d-1 is in an uneven and rough surface along the first recessed portion 106-1.

In operation 305, a second recessed portion 106-2 is formed as in FIG. 4E. In some embodiments, the second recessed portion 106-2 is formed from the portion 102 b-1 of the first metallic structure 102 a-1 to a portion 102 b-2 of the second metallic structure 102 a-2, so that the portion 102 b-2 is exposed. In some embodiments, the second recessed portion 106-2 is formed by etching of the first insulating layer 103-1 and the second insulating layer 103-2. The second recessed portion 106-2 passes from the first semiconductor chip 101-1 to the second semiconductor chip 101-2. The second recessed portion 106-2 is extended from the bottom surface of the first recessed portion 106-1 towards the second metallic structure 102 a-2.

In some embodiments, the second recessed portion 106-2 includes the second sidewall 103 d-2 and a bottom surface coplanar with the portion 102 b-2 of the second metallic structure 102 a-2. In some embodiments, the bottom surface of the second recessed portion 106-2 is disposed on or within the second metallic structure 102 a-2. In some embodiments, the first recessed portion 106-1 is coupled within the second recessed portion 106-2. In some embodiments, the first recessed portion 106-1 is disposed above the second recessed portion 106-2. In some embodiments, the second recessed portion 106-2 is surrounded by the first insulating layer 103-1 and the second insulating layer 103-2.

In operation 306, a dielectric layer 104 is formed as in FIG. 4F. In some embodiments, the dielectric layer 104 is coated on the top surface 101 a of the first semiconductor chip 101-1, the first sidewall 103 d-1 of the first recessed portion 106-1, the second sidewall 103 d-2 of the second recessed portion 106-1, the portion 102 b-1 of the first metallic structure 102 a-1 and the portion 102 b-2 of the second metallic structure 102 a-2. In some embodiments, the dielectric layer 104 is a coating including non-conductive material such as silicon dioxide. In some embodiments, the dielectric layer 104 covers and fills the staggered portions 103 e in order to smoothen the rough surface of the first sidewall 103 d-1 of the first recessed portion 106-1.

In operation 307, some portions of the dielectric layer 104 on the portion 102 b-1 of the first metallic structure 101-1 and the portion 102 b-2 of the second metallic structure 101-2 are removed as in FIG. 4G. In some embodiments, some portions of the dielectric layer 104 are dissolved and removed by etching, so that the portion 102 b-1 of the first metallic structure 102 a-1 and the portion 102 b-2 of the second metallic structure 102 a-2 are then exposed.

In operation 308, a conductive material 105 is formed on the dielectric layer 104, the portion 102 b-1 of the first metallic structure 102 a-1 and the portion 102 b-2 of the second metallic structure 102 a-2 as in FIG. 411. In some embodiments, the conductive material 105 is formed by electroplating or sputtering. The first metallic structure 102 a-1 is then electrically connected with the second metallic structure 102 a-2 via the conductive material 105 passing from the top surface 101 a, the first recessed portion 106-1 to the second recessed portion 106-2. In some embodiments, the conductive material 105 includes gold, silver, copper, nickel, tungsten, aluminum, palladium and/or alloys thereof.

In some embodiments, a semiconductor device structure includes a first chip including a plurality of dielectric layers and a multi-layered metal structure embedded in the plurality of dielectric layer, a second chip bonded to the first chip to generate a bonding interface and including a metal structure, a first via structure extending through the first chip and crossing the bonding interface into the metal structure in the second chip, and a second via structure extending in the first chip and electrically connected to the multi-layered metal structure in the first chip. The first via structure further includes a first via metal and a first via dielectric layer, the first via dielectric layer interposes between the first via metal and the plurality of dielectric layers of the first chip, and extends from the first chip to the metal structure in the second chip.

In some embodiments, the second via structure includes the a second via metal and a second via dielectric layer interposed between the second via metal and the dielectric layers of the first chip. In some embodiments, the plurality of dielectric layers include a staggered portion adjacent to a sidewall of the first via metal and is covered by the first via dielectric layer. In some embodiments, a surface roughness of the staggered portion is substantially greater than a surface roughness of the first via dielectric layer. In some embodiments, at least one of the multi-layered metal structure or the metal structure is embedded in inter metal dielectric (IMD) layers. In some embodiments, the IMD layers include low-k dielectric material. In some embodiments, the IMD layers include at least two adjacent layers having different etching rates with respect to an etchant.

In some embodiments, a semiconductor device structure includes a first chip including a multi-layered metal structure and a plurality of dielectric layers surrounding the multi-layered metal structure, a second chip bonded to the first chip to generate a bonding interface, and a via structure. The via structure includes a first portion and a second portion. The first portion extends from the first chip and crosses the bonding interface to a metal structure in the second chip. The second portion extends in the first chip to the multi-layered metal structure in the first chip. The first portion of the via structure includes a via dielectric layer interposed between the plurality of dielectric layers of the first chip and a via metal, and extends through the bonding interface to the metal structure in the second chip.

In some embodiments, the plurality of dielectric layers include a staggered portion adjacent to a sidewall of the via metal and is covered by the via dielectric layer. In some embodiments, a surface roughness of the staggered portion is substantially greater than a surface roughness of the via dielectric layer. In some embodiments, at least one of the multi-layered metal structure in the first chip or the metal structure in the second chip is embedded in inter metal IMD layers. In some embodiments, the IMD layers include low-k dielectric material. In some embodiments, the IMD layers include at least two adjacent layer having different etching rates with respect to an etchant. In some embodiments, the via metal of the via structure electrically connects the multi-layered metal structure in the first chip and the metal structure in the second chip.

In some embodiments, a semiconductor device structure includes a first chip including a plurality of dielectric layers and a first metal structure embedded in the plurality of dielectric layers, a second chip bonded to the first chip to generate a bonding interface and including a second metal structure, and a first via structure. The first via structure extends through the plurality of dielectric layers of the first chip, crosses the bonding interface, and extends through a portion of the second chip to the second metal structure in the second chip. The first via structure includes a first via metal and a first via dielectric layer. The first via dielectric layer extends to the second metal structure in the second chip, and is interposed between the first via metal and the plurality of dielectric layers of the first chip, and between the first via metal and the portion of the second chip.

In some embodiments, at least one of the first metal structure or second metal structure includes a multi-layered metal structure. In some embodiments, the plurality of dielectric layers include a staggered portion adjacent to the first via metal, the staggered portion is covered by the first via dielectric layer, and a surface roughness of the staggered portion is substantially greater than a surface roughness of the first via dielectric layer. In some embodiments, semiconductor device structure further includes a second via structure extending in the first chip and electrically connects the first metal structure in the first chip. In some embodiments, the second via structure includes a second via metal and a second via dielectric layer, the second via metal is electrically connected to the first metal structure, and the second via dielectric layer is arranged on a sidewall of the second via metal. In some embodiments, the first via metal is in contact with the second via metal, and the first via dielectric layer is in contact with the second via dielectric layer.

The methods and features of this disclosure have been sufficiently described in the above examples and descriptions. It should be understood that any modifications or changes without departing from the spirit of the disclosure are intended to be covered in the protection scope of the disclosure.

Moreover, the scope of the present application in not intended to be limited to the particular embodiments of the process, machine, manufacture, and composition of matter, means, methods and steps described in the specification. As those skilled in the art will readily appreciate from the disclosure of the present disclosure, processes, machines, manufacture, composition of matter, means, methods or steps presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein maybe utilized according to the present disclosure.

Accordingly, the appended claims are intended to include within their scope such as processes, machines, manufacture, compositions of matter, means, methods or steps. In addition, each claim constitutes a separate embodiment, and the combination of various claims and embodiments are within the scope of the disclosure. 

1. A semiconductor device structure comprising: a first chip comprising a plurality of dielectric layers and a multi-layered metal structure embedded in the plurality of dielectric layers; a second chip bonded to the first chip to generate a bonding interface, and the second chip comprising a metal structure; a first via structure extending through the first chip and crossing the bonding interface into the metal structure in the second chip; and a second via structure extending in the first chip and electrically connected to the multi-layered metal structure in the first chip, wherein the first via structure comprises a first via metal and a first via dielectric layer, the first via dielectric layer interposes between the first via metal and the plurality of dielectric layers of the first chip, and extends from the first chip to the metal structure in the second chip.
 2. The semiconductor device structure of claim 1, wherein the second via structure comprises a second via metal and a second via dielectric layer interposed between the second via metal and the dielectric layers of the first chip.
 3. The semiconductor device structure of claim 1, wherein the plurality of dielectric layers comprise a staggered portion adjacent to a sidewall of the first via metal and is covered by the first via dielectric layer.
 4. The semiconductor device structure of claim 3, wherein a surface roughness of the staggered portion is substantially greater than a surface roughness of the first via dielectric layer.
 5. The semiconductor device structure of claim 1, wherein at least one of the multi-layered metal structure or the metal structure is embedded in inter metal dielectric (IMD) layers.
 6. The semiconductor device structure of claim 5, wherein the IMD layers comprise low-k dielectric material.
 7. The semiconductor device structure of claim 5, wherein the IMD layers comprise at least two adjacent layers having different etching rates with respect to an etchant.
 8. A semiconductor device structure comprising: a first chip comprising a multi-layered metal structure and a plurality of dielectric layers surrounding the multi-layered metal structure; a second chip bonded to the first chip to generate a bonding interface; and a via structure comprising: a first portion extending from the first chip and crossing the bonding interface to a metal structure in the second chip; and a second portion extending in the first chip to the multi-layered metal structure in the first chip, wherein the first portion of the via structure comprises a via dielectric layer interposed between the plurality of dielectric layers of the first chip and a via metal, and extends through the bonding interface to the metal structure in the second chip.
 9. The semiconductor device structure of claim 8, wherein the plurality of dielectric layers comprise a staggered portion adjacent to a sidewall of the via metal and is covered by the via dielectric layer.
 10. The semiconductor device structure of claim 9, wherein a surface roughness of the staggered portion is substantially greater than a surface roughness of the via dielectric layer.
 11. The semiconductor device structure of claim 8, wherein at least one of the multi-layered metal structure in the first chip or the metal structure in the second chip is embedded in inter metal dielectric (IMD) layers.
 12. The semiconductor device structure of claim 11, wherein the IMD layers comprise low-k dielectric material.
 13. The semiconductor device structure of claim 11, wherein the IMD layers comprise at least two adjacent layers having different etching rates with respect to an etchant.
 14. The semiconductor device structure of claim 11, wherein the via metal of the via structure electrically connects the multi-layered metal structure in the first chip and the metal structure in the second chip.
 15. A semiconductor device structure comprising: a first chip comprising a plurality of dielectric layers and a first metal structure embedded in the plurality of dielectric layers; a second chip bonded to the first chip to generate a bonding interface, the second chip comprising a second metal structure; and a first via structure extending through the plurality of dielectric layers of the first chip, crossing the bonding interface and extending through a portion of the second chip to the second metal structure in the second chip; wherein the first via structure comprises a first via metal and a first via dielectric layer, the first via dielectric layer extends to the second metal structure in the second chip and is interposed between the first via metal and the plurality of dielectric layers of the first chip, and between the first via metal and the portion of the second chip.
 16. The semiconductor device structure of claim 15, wherein at least one of the first metal structure or the second metal structure comprises a multi-layered metal structure.
 17. The semiconductor device structure of claim 15, the plurality of dielectric layers comprise a staggered portion adjacent to the first via metal, the staggered portion is covered by the first via dielectric layer, and a surface roughness of the staggered portion is substantially greater than a surface roughness of the first via dielectric layer.
 18. The semiconductor device structure of claim 15, further comprising a second via structure extending in the first chip and electrically connects the first metal structure in the first chip.
 19. The semiconductor device structure of claim 18, wherein the second via structure comprises a second via metal and a second via dielectric layer, the second via metal is electrically connected to the first metal structure, and the second via dielectric layer is arranged on a sidewall of the second via metal.
 20. The semiconductor device structure of claim 19, wherein the first via metal is in contact with the second via metal, and the first via dielectric layer is in contact with the second via dielectric layer. 